抑制miR-155-5p通过AMPK信号通路调控衰老的间充质干细胞年轻化治疗心肌梗死的机制研究

Accumulating evidence has demonstrated that mesenchymal stem cells (MSCs) based therapy is a novel strategy for myocardial infarction (MI). However, the function of MSCs declines with age, thus limiting the therapeutic efficacy. Therefore, rejuvenating MSCs from the aged people (aged-MSCs) is of great importance. Previous studies have revealed that the balance of mitochondrial fission and fusion plays a critical role in MSCs aging, but the potential mechanism has not been totally understood. Our previous study has shown that compared with the MSCs from young people's bone marrow (young-MSCs), the expression of miR-155-5p and mitochondrial fusion were greatly enhanced whereas the mitochondrial fission, Cab39 and p-AMPK were significantly reduced in the aged-MSCs, indicating that miR-155-5p may be involved in regulating MSCs aging. Cab39, an upstream gene of AMPK signaling pathway, is a target gene of miR-155-5p. Therefore, in the present study, we focus on investigating the potential mechanisms of miR-155-5p inducing MSCs aging via regulating the Cab39/AMPK signaling pathway to mediate the balance of mitochondrial fission and fusion. Subsequently, we will also reveal the potential mechanisms of the inhibition of miR-155-5p rejuvenating aged-MSCs and assess the therapeutic effects of anti-miR-155-5p-aged-MSCs on the MI model in mice. This study will provide novel insights for the development of new strategy for MI.

研究证实间充质干细胞（mesenchymal stem cells, MSCs）对心肌梗死具有良好的疗效。然而来源于老年人的MSCs，衰老且功能下降，因而限制其疗效。线粒体的分裂和融合在MSCs的衰老中起着重要的作用，然而其潜在的机制尚未完全明了。我们前期实验发现与年轻人的骨髓MSCs相比较，老年人的MSCs中miR-155-5p表达显著升高，同时线粒体的融合增多、分裂减少，Cab39和p-AMPK降低，提示miR-155-5p参与MSCs的衰老。Cab39, AMPK通路的一个上游基因，是miR-155-5p的一个靶点基因。本课题在研究miR-155-5p通过调节Cab39/AMPK通路从而导致线粒体的分裂和融合失衡而诱导MSCs衰老机制的基础上，进一步研究通过抑制miR-155-5p使衰老的MSCs年轻化而增强其对心肌梗死的疗效。此研究将为开拓心肌梗死治疗新方法提供相关的理论基础。

背景：间充质干细胞（mesenchymal stem cells, MSCs）对心肌梗死具有良好的疗效。然而，来源于老年人的MSCs功能下降，因而限制其疗效。因此，如何使衰老的MSC年轻化增强其功能具有非常重要的研究意义。我们前期研究发现:1）与年轻人的骨髓MSCs（YMSCs）相比较，老年人的MSCs(AMSCs) 中miR-155-5p表达显著升高，2) 线粒体的融合增多、分裂减少; 3) Cab39和p-AMPK表达量降低。Cab39是miR-155-5p的一个靶点基因。本项目主要系统地研究miR-155-5p调控MSC衰老的机制，并进一步研究通过抑制miR-155-5p使衰老的MSCs年轻化而增强其对小鼠心肌梗死的治疗作用， 从而为开拓心肌梗死治疗新方法提供相关的理论基础。重要结果如下：1）与YMSCs相比较，AMSCs的增殖，分化，旁分泌功能明显下降，线粒体融合增多，SA-β-gal阳性率升高，提示AMSCs明显衰老；2）miR-155-5p 通过调控MSCs的线粒体形态诱导MSCs的衰老；3) miR-155-5p 通过Cab39/AMPK通路调控MSCs的线粒体的融合而诱导MSC衰老；4）抑制miR-155-5p可促进线粒体的分裂诱导AMSCs的年轻化；5）建立anti- miR-155-5p-AMSCs的细胞系。 与AMSCs相比较，移植anti-miR-155-5p-AMSCs对小鼠的心肌梗死有着更好的保护作用。意义：本研究揭示了miR-155-5p通过Cab39/AMPK通路介导线粒体的形态的变化从而调控MSC的衰老；抑制miR-155-5p 可使AMSC年轻化，增强其对心肌梗死的疗效。本课题为MSCs 在心血管疾病的临床治疗提供理论依据和实验基础。目前本课题共发表SCI论文8篇（其中IF>7一篇，>6一篇），培养研究生3人。